To study how two types of testing protocols for the determination of the [LA] and
blood pH kinetics during running match each other, a group of nine runners participated
in two testing protocols. The first protocol consisted of a sequences of 8 x 2000
m runs at constant speed, which was increased on different testing days. The first
protocol was used for the determination of running speed (v), [LA], pH and heart rate
(HR) corresponding to the Lactate Threshold (LT) and the Threshold of Acidosis (TA),
both occurring at similar running speeds (4.21 ± 0.44 and 4.22 ± 0.40 m/s) (mean ±
SD) and HR (159 ± 7 and 160 ± 9 1/min), [LA] = 2.0 ± 0.6 mmol/l and pH = 7.411 ± 0.018.
Maximal steady values for [LA] (maxLAss) and minimal steady values for pH (minpHss)
obtained by the second protocol were higher (p < 0.01) according to running speed
(4.62 ± 0.38 and 4.66 ± 0.38 m/s), HR (172 ± 7 and 174 ± 8 1/min)and [LA] (5.7 ± 1.3
mmol/l) and lower according to pH (7.364 ± 0.021), respectively. Unlike similar running
speeds determined by LT and TA, the minimal steady pH level occurred at a slightly
higher speed than the speed at maxLAss. Additionally, we found a drift of pH towards
a resting level, when [LA] fluctuated around a steady level. Furthermore, the parameters
of pH kinetics correlated better with the running speed of the 4000 m run that was
taken as the parameter of short endurance performance, than those of [LA] kinetics.
We conclude that these differences in [LA] and pH kinetics could serve to predict
the capabilities of runners with respect to the two endurance performance types: long
and short.
Key words
Lactate - blood pH - heart rate - kinetic analysis - running endurance
